Memory bit flips happen all the time—not like daily or weekly per computer, but you can have multiple memory bit flip incidents during the multi-year life of an

Memory bit flips happen all the time—not like daily or weekly per computer, but you can have multiple memory bit flip incidents during the multi-year life of an average computer. Either you detect them, or you get silent data corruption. If you're lucky it's in unused ram; if you're not, it may be in running code (possible crash or software misbehavior) or data (in a text document, one corrupted character; in some other kind of data, it could be much worse). Think about how a bit flip in code or data can affect things like ciphertext generation. It can become a huge deal. Think of "bad ram" —the kind that fails memtest86— as ram that has an increased tendency (compared to "good ram") to flip certain bits that with a little more luck, or more conservative timings, wouldn't flip. The threshold between good ram and bad ram is not black and white. Also see "rowhammer" — https://news.ycombinator.com/item?id=9171722 https://news.ycombinator.com/item?id=9171722 — ECC mitigates that to a significant degree. Aggressive memory testing before use can weed out memory that's plain bad (one bit always screwing up), and certain borderline cases of memory that will flip bits under certain high stress loads or access patterns (I suppose that's due to thermal entropy?), but it's no guarantee, and it certainly offers no protection against cosmic ray induced bit flips, which happen too. Ordinary consumer memory is not "quite reliable" if you care about data integrity or stability. Google's study: http://research.google.com/pubs/pub35162.html http://research.google.com/pubs/pub35162.html (direct pdf link: http://static.googleusercontent.com/media/research.google.com/en//pubs/archive/35162.pdf http://static.googleusercontent.com/media/research.google.co... )